<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Null</title>
</head>
<body>
</body>
<script>
    let human = null;

    console.log("human =", human); // human = null

    // 赋值一个新对象
    human = new Object();
    if (human != null) {
        console.log("human已经赋值");
    }
</script>
</html>